In many applications, it is desirable to controllably deflect concentrated beams of electromagnetic energy (i.e., concentrated light beams) that originate from a fixed or moving light beam source. A short list of such applications includes scanning pictures onto video monitors, scanning information from bar codes, performing medical procedures, creating projected visual displays, e.g., for light shows, as well as for use in creating optical connections. Depending upon the specific application, it may be desirable to deflect concentrated light beams of multiple wavelength (polychromatic) visible light, monochromatic light (i.e., lasers) as well as non-visible light (e.g., ultraviolet or infrared light). In any case, a light beam deflector, which may include one or more selectively controllable mirrors, is typically utilized to redirect a concentrated light beam to a desired position in space or in a desired pattern.
In single mirror light beam deflectors, a mirror is generally interconnected to one or more mechanical control devices for adjusting the orientation of the mirror relative to the light beam source. For example, in some applications a mirror is affixed to an output shaft of a motor that is capable of oscillating the mirror relative to a fixed plane in order to allow for the line by line scanning of pictures, e.g., in a raster pattern. In other applications, mirrors may be capable of tilting about two perpendicular axes to allow the mirror to be oriented in any of a number of planes extending through the intersection of the axes. Accordingly, a light beam may be deflected to substantially any point in space as limited by the range of movement of the mirror about the axes.
Each of the above deflectors (i.e., oscillating and two axes tilting), while being well suited for some applications, are often of limited value in applications requiring multiple degrees of mirror freedom for directing a light beam in complex patterns. For example, oscillating deflectors while being well suited for line by line scanning application often have a limited operating range as well as a mirror fixed in a single plane. Furthermore, two axes tilting mirror deflectors tend to be mechanically intricate and often require complex control signals in order to adjust the deflector's mirror to a desired orientation. In this regard, these deflectors are of limited value in scanning and graphic applications where it is desirable to rapidly scan a beam across a surface in a controlled manner. That is, periodic, harmonic or other complex light deflection patterns may require unduly complex control signals that require expanded processing and control systems and/or require feedback to properly direct a deflected light beam to a point in space. Furthermore, deflection about two axes often results in translating the mirror relative to a fixed reference point. That is, the tilting of the mirror about two axis often shifts the position of the mirror relative to a fixed light beam source. Accordingly, this relative movement between the mirror and the light source may change the distance and/or angle between the light source and mirror introducing additional complexities in generation of control signals for use in directing a light beam in a desired manner.